This invention relates to communications systems and, more particularly, to a packet compression/expansion system for very high speed optical communication networks.
Multi-user lightwave packet networks have attracted a great deal of interest because of their potential for enormous aggregate capacity, estimated to be in the range of several tens of terabits per second. This large capacity, coupled with the ability to readily integrate multimedia traffic on high speed, self-routing packet streams, invites a number of new, broadband forms of telecommunications services. A fundamental constraint, however, is the so-called electro-optic bottleneck, which restricts the access rate of any one user (or any one network port) to a range no greater than several gigabits per second.
Wavelength division multiplexing has been considered a possible means to create and share a large capacity pool (terabits/second) among a multitude of relatively lower speed network ports. To provide packet-by-packet connectivity, one such scheme, described in an article by L. G. Kazovsky entitled "Multichannel Coherent Optical Communications Systems" published in Journal of Lightwave Technology, Vol. LT-5, No. 8, pp. 1 095-1102, 1987, and in a paper by B. Glance et al. entitled "Densely Spaced WDM Optical Star Network", published in Electron. Lett. vol. 22, no. 19, pp. 1002-1003, 1986, requires optical elements (lasers and optical filters) tunable over the entire range of active wavelengths on a time scale short as compared to the packet length, plus a fast controller or scheduler to nonconflictingly assign wavelengths to user transmitter/receiver pairs on a packet-by-packet basis. Another scheme described in articles authored by applicant and others entitled "A Multichannel Multihop Local Lightwave Network" published in IEEE Globecom '87 Conference Record, Tokyo, Nov. 1987, and "Terabit Lightwave Networks: A Multihop Approach" published in AT&T Technical Journal, Vol. 66, No. 6, Nov./Dec. 1987, requiring neither wavelength agility nor a fast controller, involves passing each packet among the nodes of the network, which are connected in a recirculating perfect shuttle pattern with a different wavelength corresponding to each link. Electronic regeneration, storage and retransmission on a different link (wavelength) occurs at each such relaying node until the packet reaches its intended destination.